The field of the invention is sterile drapes for surgical microscopes.
Microscopes are often used in surgical procedures. In many of these procedures, such as neuro surgery and plastic surgery, the surgeon must manipulate exceptionally small blood vessels, nerve bundles, muscles, nerves and other tissue. These procedures require viewing the surgical site through a surgical microscope, so that the fine details in the surgical site can be clearly seen by the surgeon.
The area around the surgical site must be maintained sterile. As it is difficult or impossible to sterilize the surgical microscope, it is common practice to cover the microscope with a sterile drape. However, the sterile drape must not interfere with the view of the surgical site through the objective lens of the microscope. Accordingly, devices have been provided to allow surgical microscopes to be covered with a sterile drape, while not interfering with the objective lens. For example, Pederson et al., U.S. Pat. No. 5,311,358, discloses a universal microscope drape having an adapter ring with the ring fitting between the objective lens and the rest of the microscope. The objective lens must be removed to install the adapter ring.
However, various disadvantages have been realized in trying to adapt sterile drapes to surgical microscopes. One disadvantage arises because most hospitals have two or more different types of surgical microscopes. As the dimensions of the objective lenses of different microscopes have different dimensions, sterile drapes having different drape rings must be supplied and stored at the hospital. Consequently, the logistics of setting up the operating room before surgery are more complicated, as the correct surgical drape must be selected to match the particular microscope in that operating room. If the incorrect drape is selected, the operation will be delayed while the correct drape is identified, located and installed. The opened incorrect drape is then necessarily discarded and wasted. In addition, the outside diameters of the objective lens on several surgical microscopes can be so near to each other that an incorrect drape could be inadvertently placed onto a microscope which it is not designed to properly fit. As a result, the sterile barrier function of the drape may not be fully realized.
Another disadvantage in draping surgical microscopes is that with some drapes, the mounting ring has an injection molded lens, which can cause distortion. As a result, some surgeons will simply discard the plastic lens. When this occurs, the contaminated objective lens of the surgical microscope itself is exposed to blood, and other fluids, so that frequent cleaning may be required. This exposure and cleaning of the objective lens increases the potential for scratching or damage to the objective lens, an expensive component of the surgical microscope.
Where surgical drapes have mounting rings or adapters which fit between the objective lens and the other lenses in the surgical microscope, the distance between the lenses may be changed, thereby changing the focusing characteristics of the microscope. Accordingly, there remains a need for a sterile drape for a surgical microscope which provides a sterile barrier without changing the focal length of the microscope.